/*
 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.lang;


/**
 * A mutable sequence of characters.  This class provides an API compatible
 * with {@code StringBuffer}, but with no guarantee of synchronization.
 * This class is designed for use as a drop-in replacement for
 * {@code StringBuffer} in places where the string buffer was being
 * used by a single thread (as is generally the case).   Where possible,
 * it is recommended that this class be used in preference to
 * {@code StringBuffer} as it will be faster under most implementations.
 *
 * <p>The principal operations on a {@code StringBuilder} are the
 * {@code append} and {@code insert} methods, which are
 * overloaded so as to accept data of any type. Each effectively
 * converts a given datum to a string and then appends or inserts the
 * characters of that string to the string builder. The
 * {@code append} method always adds these characters at the end
 * of the builder; the {@code insert} method adds the characters at
 * a specified point.
 * <p>
 * For example, if {@code z} refers to a string builder object
 * whose current contents are "{@code start}", then
 * the method call {@code z.append("le")} would cause the string
 * builder to contain "{@code startle}", whereas
 * {@code z.insert(4, "le")} would alter the string builder to
 * contain "{@code starlet}".
 * <p>
 * In general, if sb refers to an instance of a {@code StringBuilder},
 * then {@code sb.append(x)} has the same effect as
 * {@code sb.insert(sb.length(), x)}.
 * <p>
 * Every string builder has a capacity. As long as the length of the
 * character sequence contained in the string builder does not exceed
 * the capacity, it is not necessary to allocate a new internal
 * buffer. If the internal buffer overflows, it is automatically made larger.
 *
 * <p>Instances of {@code StringBuilder} are not safe for
 * use by multiple threads. If such synchronization is required then it is
 * recommended that {@link java.lang.StringBuffer} be used.
 *
 * <p>Unless otherwise noted, passing a {@code null} argument to a constructor
 * or method in this class will cause a {@link NullPointerException} to be
 * thrown.
 *
 * @author Michael McCloskey
 * @see java.lang.StringBuffer
 * @see java.lang.String
 * @since 1.5
 */
public final class StringBuilder
    extends AbstractStringBuilder
    implements java.io.Serializable, CharSequence {

  /**
   * use serialVersionUID for interoperability
   */
  static final long serialVersionUID = 4383685877147921099L;

  /**
   * Constructs a string builder with no characters in it and an
   * initial capacity of 16 characters.
   */
  public StringBuilder() {
    super(16);
  }

  /**
   * Constructs a string builder with no characters in it and an
   * initial capacity specified by the {@code capacity} argument.
   *
   * @param capacity the initial capacity.
   * @throws NegativeArraySizeException if the {@code capacity} argument is less than {@code 0}.
   */
  public StringBuilder(int capacity) {
    super(capacity);
  }

  /**
   * Constructs a string builder initialized to the contents of the
   * specified string. The initial capacity of the string builder is
   * {@code 16} plus the length of the string argument.
   *
   * @param str the initial contents of the buffer.
   */
  public StringBuilder(String str) {
    super(str.length() + 16);
    append(str);
  }

  /**
   * Constructs a string builder that contains the same characters
   * as the specified {@code CharSequence}. The initial capacity of
   * the string builder is {@code 16} plus the length of the
   * {@code CharSequence} argument.
   *
   * @param seq the sequence to copy.
   */
  public StringBuilder(CharSequence seq) {
    this(seq.length() + 16);
    append(seq);
  }

  @Override
  public StringBuilder append(Object obj) {
    return append(String.valueOf(obj));
  }

  @Override
  public StringBuilder append(String str) {
    super.append(str);
    return this;
  }

  /**
   * Appends the specified {@code StringBuffer} to this sequence.
   * <p>
   * The characters of the {@code StringBuffer} argument are appended,
   * in order, to this sequence, increasing the
   * length of this sequence by the length of the argument.
   * If {@code sb} is {@code null}, then the four characters
   * {@code "null"} are appended to this sequence.
   * <p>
   * Let <i>n</i> be the length of this character sequence just prior to
   * execution of the {@code append} method. Then the character at index
   * <i>k</i> in the new character sequence is equal to the character at
   * index <i>k</i> in the old character sequence, if <i>k</i> is less than
   * <i>n</i>; otherwise, it is equal to the character at index <i>k-n</i>
   * in the argument {@code sb}.
   *
   * @param sb the {@code StringBuffer} to append.
   * @return a reference to this object.
   */
  public StringBuilder append(StringBuffer sb) {
    super.append(sb);
    return this;
  }

  @Override
  public StringBuilder append(CharSequence s) {
    super.append(s);
    return this;
  }

  /**
   * @throws IndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder append(CharSequence s, int start, int end) {
    super.append(s, start, end);
    return this;
  }

  @Override
  public StringBuilder append(char[] str) {
    super.append(str);
    return this;
  }

  /**
   * @throws IndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder append(char[] str, int offset, int len) {
    super.append(str, offset, len);
    return this;
  }

  @Override
  public StringBuilder append(boolean b) {
    super.append(b);
    return this;
  }

  @Override
  public StringBuilder append(char c) {
    super.append(c);
    return this;
  }

  @Override
  public StringBuilder append(int i) {
    super.append(i);
    return this;
  }

  @Override
  public StringBuilder append(long lng) {
    super.append(lng);
    return this;
  }

  @Override
  public StringBuilder append(float f) {
    super.append(f);
    return this;
  }

  @Override
  public StringBuilder append(double d) {
    super.append(d);
    return this;
  }

  /**
   * @since 1.5
   */
  @Override
  public StringBuilder appendCodePoint(int codePoint) {
    super.appendCodePoint(codePoint);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder delete(int start, int end) {
    super.delete(start, end);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder deleteCharAt(int index) {
    super.deleteCharAt(index);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder replace(int start, int end, String str) {
    super.replace(start, end, str);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int index, char[] str, int offset,
      int len) {
    super.insert(index, str, offset, len);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int offset, Object obj) {
    super.insert(offset, obj);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int offset, String str) {
    super.insert(offset, str);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int offset, char[] str) {
    super.insert(offset, str);
    return this;
  }

  /**
   * @throws IndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int dstOffset, CharSequence s) {
    super.insert(dstOffset, s);
    return this;
  }

  /**
   * @throws IndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int dstOffset, CharSequence s,
      int start, int end) {
    super.insert(dstOffset, s, start, end);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int offset, boolean b) {
    super.insert(offset, b);
    return this;
  }

  /**
   * @throws IndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int offset, char c) {
    super.insert(offset, c);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int offset, int i) {
    super.insert(offset, i);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int offset, long l) {
    super.insert(offset, l);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int offset, float f) {
    super.insert(offset, f);
    return this;
  }

  /**
   * @throws StringIndexOutOfBoundsException {@inheritDoc}
   */
  @Override
  public StringBuilder insert(int offset, double d) {
    super.insert(offset, d);
    return this;
  }

  @Override
  public int indexOf(String str) {
    return super.indexOf(str);
  }

  @Override
  public int indexOf(String str, int fromIndex) {
    return super.indexOf(str, fromIndex);
  }

  @Override
  public int lastIndexOf(String str) {
    return super.lastIndexOf(str);
  }

  @Override
  public int lastIndexOf(String str, int fromIndex) {
    return super.lastIndexOf(str, fromIndex);
  }

  @Override
  public StringBuilder reverse() {
    super.reverse();
    return this;
  }

  @Override
  public String toString() {
    // Create a copy, don't share the array
    return new String(value, 0, count);
  }

  /**
   * Save the state of the {@code StringBuilder} instance to a stream
   * (that is, serialize it).
   *
   * @serialData the number of characters currently stored in the string builder ({@code int}),
   * followed by the characters in the string builder ({@code char[]}).   The length of the {@code
   * char} array may be greater than the number of characters currently stored in the string
   * builder, in which case extra characters are ignored.
   */
  private void writeObject(java.io.ObjectOutputStream s)
      throws java.io.IOException {
    s.defaultWriteObject();
    s.writeInt(count);
    s.writeObject(value);
  }

  /**
   * readObject is called to restore the state of the StringBuffer from
   * a stream.
   */
  private void readObject(java.io.ObjectInputStream s)
      throws java.io.IOException, ClassNotFoundException {
    s.defaultReadObject();
    count = s.readInt();
    value = (char[]) s.readObject();
  }

}
